Expander warns about unbound variables.

* eval.c (eval_exception): New static function.
(eval_error): Reduced to wrapper around eval_exception.
(eval_warn): New function.
(me_op): Bind the rest symbol in a shadowing env to suppress
watnings about unbound rest.
(do_expand): Throw a warning when a bindable symbol is
traversed that has no binding.
(expand): Don't install atoms as last_form_expanded.

* lib.c (warning_s, restart_s, continue_s): New symbol
variables.
(obj_init): Initialize new symbol variables.

* lib.h (warning_s, restart_s, continue_s): Declared.

* lisplib.c (except_set_entries): New entries for
ignwarn and macro-time-ignwarn.

* parser.c (repl_warning): New static function.
(repl): Use repl_warning function as a handler for
warning exceptions: to print their message and then
continue by throwing a continue exception.

* parser.y (warning_continue): New static function.
(parse_once): Use warning_continue to ignore warnings.
In other words, we suppress warnings from Lisp that is
mixed into TXR pattern language code, because this
produces too many false positives.

* share/txr/stdlib/except.tl (ignwarn, macro-time-ignwarn):
New macros.

* share/txr/stdlib/place.tl (call-update-expander,
call-clobber-expander, call-delete-expander): Ignore warnings
around calls to sys:expand, because of some gensym-related
false positives (we expand code into which we inserted some
gensyms, without having inserted the constructs which
bind them.

* tests/011/macros-2.txr: Suppress unbound variable
warnings from a test case.

* tests/012/ifa.tl: Bind unbound x y variables in one
test case.

* tests/012/struct.tl: Suppress unbound variable
warnings in some test cases.

* uwind.c (uw_throw): If a warning is unhandled, then
print its message with a "warning" prefix and then
throw a continue exception.
(uw_register_subtype): Eliminate the check for sub
already being a subtype of sup. This allows us to
officially register new types against t.
(uw_late_init): Register continue exception type as a
subtype of the restart type.
Formally register warning type.

* txr.1: Documented ignwarn.

1 files changed, 9 insertions, 4 deletions

diff --git a/unwind.c b/unwind.c
index a79a69bd..a993e7cf 100644
--- a/unwind.c
+++ b/unwind.c
@@ -556,6 +556,13 @@ val uw_throw(val sym, val args)
       abort();
     }
 
+    if (sym == warning_s) {
+      --reentry_count;
+      format(std_error, lit("warning: ~a\n"), car(args), nao);
+      uw_throw(continue_s, nil);
+      abort();
+    }
+
     {
       loc pfun = lookup_var_l(nil, unhandled_hook_s);
       val fun = deref(pfun);
@@ -667,10 +674,6 @@ val uw_register_subtype(val sub, val sup)
               sub, sup, nao);
   }
 
-  if (uw_exception_subtype_p(sub, sup))
-    uw_throwf(type_error_s, lit("~s is already an exception subtype of ~s"),
-              sub, sup, nao);
-
   if (uw_exception_subtype_p(sup, sub))
     uw_throwf(type_error_s, lit("~s is already an exception supertype of ~s"),
               sub, sup, nao);
@@ -975,4 +978,6 @@ void uw_late_init(void)
           func_n2v(uw_invoke_catch));
   reg_fun(sys_capture_cont_s = intern(lit("capture-cont"), system_package),
           func_n3o(uw_capture_cont, 2));
+  uw_register_subtype(continue_s, restart_s);
+  uw_register_subtype(warning_s, t);
 }